1. Field of the Invention
The present invention relates to an optical device for emitting a laser beam and an image forming apparatus with the optical device incorporated therein.
2. Description of the Related Art
With development of optical technologies, optical devices for emitting a laser beam are used in various technological fields. Typically, an optical device includes a sensor configured to detect a laser beam for the purpose of detecting operation of the optical device, synchronizing with operation of another arbitrary apparatus used with the optical device or obtaining other desired results.
An image forming apparatus such as a copier, a printer, a facsimile machine or a complex machine provided with these functions employs, as the aforementioned optical device, an exposure device configured to irradiate a laser beam to a circumferential surface of a photoconductive drum to form an electrostatic latent image. In order to form a desired toner image, the exposure device typically includes a polygon mirror configured to form an optical path of the laser beam and a motor configured to rotate the polygon mirror.
A signal line extending from a sensor and a power line for supplying power to the motor are arranged in a housing of the aforementioned exposure device. The following problems are inherent in arrangement of the signal line and the power line in the housing of the exposure device.
The power line near the signal line causes noise in signals transmitted through the signal line. Accordingly, the signal line needs to be sufficiently spaced apart from the power line. Further, the signal line and the power line need to be so arranged as not to interfere with the optical path formed in the housing. Generally, the signal line and the power line are very flexible. Thus, it is more difficult to fix arrangement positions of these lines as compared with other optical elements used in the exposure device.
Due to the aforementioned problems, a conventional optical device including a drive source which requires power supply and a sensor configured to detect a laser beam is likely to have troubles such as signal noise and interception of a laser beam.